The Montreal Protocol on Substances that Deplete the Ozone Layer

The Montreal Protocol on Substances that Deplete the Ozone Layer is a global agreement to protect the Earth’s ozone layer by phasing out the chemicals that deplete it. This phase-out plan includes both the production and consumption of ozone-depleting substances. The landmark agreement was signed in 1987 and entered into force in 1989.

The parties to the Protocol meet once a year to make decisions aimed at ensuring the successful implementation of the agreement. These include adjusting or amending the Protocol, which has been done six times since its creation. The most recent amendment, the Kigali Amendment, called for the phase-down of hydrofluorocarbons (HFCs) in 2016. These HFCs were used as replacements for a batch of ozone-depleting substances eliminated by the original Montreal Protocol. Although they do not deplete the ozone layer, they are known to be powerful greenhouse gases and, thus, contributors to climate change.

The Montreal Protocol provided a set of practical, actionable tasks that were universally agreed on. The Protocol has successfully met its objectives thus far and continues to safeguard the ozone layer today. Thanks to the collaborative effort of nations around the world, the ozone layer is well on its way to recovery.

Decision XXXIII/4: Enhancing the global and regional atmospheric monitoring of substances controlled by the Montreal Protocol

Noting with appreciation decision VC XII/1 of the parties to the Vienna Convention for the Protection of the Ozone Layer approving the recommendations of the Ozone Research Managers of the Parties to the Vienna Convention at their eleventh meeting,

Recalling decision XXX/3 on unexpected emissions of trichlorofluoromethane (CFC‑11) and decision XXXI/3 on unexpected emissions of CFC-11 and institutional processes to be enhanced to strengthen the effective implementation and enforcement of the Montreal Protocol on Substances that Deplete the Ozone Layer,

Noting with appreciation the Scientific Assessment Panel’s “white paper” entitled “Closing the gaps in top-down regional emissions quantification: needs and action plan”, 1

To request the Ozone Secretariat, in consultation with relevant experts from the Scientific Assessment Panel, the Technology and Economic Assessment Panel and the Ozone Research Managers, to provide the following information to the parties at the forty-fifth meeting of the Open‑ended Working Group of the Parties to the Montreal Protocol, to be held in 2023, and to report on the progress of work at the forty-fourth meeting of the Open‑ended Working Group:

  1. Options for the regional monitoring of atmospheric concentrations of substances controlled by the Montreal Protocol, based on the existing information provided by the Scientific Assessment Panel and the Ozone Research Managers, and the challenges for operationalizing relevant recommendations;
  2. The identification of suitable locations for possible high-frequency measurements and flask sampling for regions not, or not sufficiently, covered by existing atmospheric monitoring, with a view to strengthening monitoring capacity and networks;
  3. Options for possible means of establishing new monitoring capacity and related costs, taking into account existing monitoring infrastructure.

1 UNEP/OzL/Conv.ResMgr/11/4/Rev.1, annex..